Experience is crucial to expanding CSEM use

It’s been more than 30 years since the idea of using resistivity measurements for large-scale ocean reconnaissance in exploration was first proposed in academia. In shallow water, electromagnetic energy reaching the sea surface is transmitted through the air and subsequently back through the water, swamping most of the readings coming from the geological targets, so, making sea bed resistivity measurements a commercial business would have to wait until deepwater exploration became commonplace. Obviously, both of these events have now occurred. Since 2002, over 200 sea bed electromagnetic surveys have been conducted worldwide. Data from only a few of them have been released. Companies that were not part of the original development may have seen only modest proof of the efficacy of the technology. In addition to illustrating the technique, this article presents three examples of Shell’s Sea Bed Logging (SBL) experiences.